A method for fulfilling requests in an inventory system includes receiving a request indicating an activity to be completed. The high gas permeability polybenzoxazole polymer membranes can be used for a single stage membrane system or for the first stage membrane in a two stage membrane system for natural gas upgrading. Next, at least one compensated value is derived based on the responses of the receivers to the transmitters. Thus, the pickup truck can be converted easily from a normal looking pickup truck for recreational and personal applications into a flat bed truck for commercial and work applications by removing and storing the side panels and the tailgate assembly.